I'm well aware that the correlation between college YPC and NFL success may not be very strong. For what it's worth, Clarett's YPC ranked 11th among RBs with 200 carries in 2002.
Larry Johnson: 271 carries, 7.7 ypc
Quentin Griffin: 282 carries, 6.6 ypc
Willis McGahee: 282 carries, 6.2 ypc
Darren Sproles: 237 carries, 6.2 ypc (who just got drafted to backup LT)
Chris Brown: 303 carries, 6.1 ypc
Joe Smith: 208 carries, 5.8 ypc
Fred Russell: 220 carries, 5.7 ypc
Terry Caulley: 220 carries, 5.7 ypc
Michael Turner: 338 carries, 5.7 ypc
Jason Wright: 219 carries, 5.6 ypc
Maurice Clarett: 222 carries, 5.6 ypc
Chris Downs: 208 carries, 5.5 ypc
Terry Jackson II: 238 carries, 5.5 ypc
Derrick Knight: 259 carries, 5.5 ypc
Other notables:
Brock Forsey: 295 carries, 5.5 ypc
Kevin Jones: 160 carries, 5.4 ypc
Steven Jackson: 319 carries, 5.3 ypc
Carnell Williams: 141 carries, 5.3 ypc
Lee Suggs: 257 carries, 5.2 ypc
Dom Davis: 193 carries, 4.8 ypc
Clarett's numbers certainly aren't bad, but they don't stand out either. He was effective on a national championship team, with phenomenal talent surrounding him. Sure Dom Davis performed worse and Quentin Griffin performed better, so it's hard to peg Clarett's NFL prospects based on this. But I certainly don't look and say "WOW, if not for his character issues this guy would be a lock to be an NFL star."
Larry Johnson: 271 carries, 7.7 ypc - Big 10 6'2", 222 - looks like he can be an NFL starterQuentin Griffin: 282 carries, 6.6 ypc - Big 12 - 5'7", 190 - Does not include short yardage situations
Willis McGahee: 282 carries, 6.2 ypc - Big East - 6'1", 224 - NFL Starter
Darren Sproles: 237 carries, 6.2 ypc (who just got drafted to backup LT) - Big 12 - 5'7", 180 - Again, no short yardage stats in there
Chris Brown: 303 carries, 6.1 ypc - Big 12 - 6'3", 220 - NFL Starter
Joe Smith: 208 carries, 5.8 ypc - WAC - 6'1", 218 - Not exactly a defensive conference
Fred Russell: 220 carries, 5.7 ypc - Big 10 - 5'8", 190 - probably not a short yardage guy.
Terry Caulley: 220 carries, 5.7 ypc - Independant - 5'7", 186 - weak schedule
Michael Turner: 338 carries, 5.7 ypc - MAC - 6"0", 228 - 2nd tier conference
Jason Wright: 219 carries, 5.6 ypc - Big 10 - 5'10", 210 - ?
Maurice Clarett: 222 carries, 5.6 ypc - Big 10 - 6'0", 230
Chris Downs: 208 carries, 5.5 ypc - ACC - 5'8", 193 - Another little guy
Terry Jackson II: 238 carries, 5.5 ypc -S. Illinois - 5'11", 195 - light schedule
Derrick Knight: 259 carries, 5.5 ypc - Big East - 5'9", 205 - no short yardage
Take away the little, obvious 3rd down type backs and the players from 2nd tier conferences and you're left with McGahee, Johnson, Brown, Clarett, St Jackson, Davis, and Suggs - all of whom are NFL caliber starters. I think Clarett's 5.6 stands up pretty well.
Also, OSU didn't have phenomenal talent around him. They had a phenomenal defense but very average offensive players. Their line was far from phenomenal. Look at the rushing averages since.